Currently, energy savings from various energy conservation projects is measured and verified using an International Performance Measurement and Verification Protocol (IPMVP) framework. The IPMVP was developed by a coalition of international organizations (led by the United States Department of Energy) in 1994-1995. Now, the IPMVP has become a national measurement and verification standard in some of the countries, including the United States, and has been translated into 10 languages. The IPMVP framework offers four specific options for quantifying the energy savings. The IPMVP suggests best practices for quantifying the results of energy efficiency investments. The IPMVP also helps in increasing investments in energy and water management, demand management and renewable energy projects.
The specific options provided by the IPMVP framework for estimating the energy consumption/savings in a site (A, B, C and D) are summarized as shown below:
a. Option (A): Retrofit Isolation: Key Parameter Measurement:
Here, the energy savings are determined by field measurement of the key performance parameter(s) which defines the energy use of the energy conservation measure's (ESS) affected system(s) and/or the success of the project. The energy estimates are derived based on historical data, manufacturer's specifications, or engineering judgment. Documentation of the source or justification of the estimated parameter is required. Typical applications of performing retrofit isolation of key parameters may include a lighting retrofit, where the power drawn can be monitored and hours of operation can be estimated.
b. Option (B): Retrofit Isolation: All Parameter Measurement:
Here, the energy savings are determined by field measurement of all the key performance parameters which define the energy use of the ESS-affected system. Typical applications may include a lighting retrofit where both power drawn and hours of operation are recorded.
c. Option (C): Whole Facility:
Here, the energy savings are determined by measuring energy use at the whole facility or sub-facility level. This approach is likely to require a regression analysis or similar to account for independent variables such as outdoor air temperature, for example. Typical examples may include measurement of a facility where several ESSs have been implemented, or where the ESS is expected to affect all equipment in a facility.
d. Option (D): Calibrated Simulation:
Here, the energy savings are determined through simulation of the energy use of the whole facility, or of a sub-facility. Simulation routines are demonstrated to adequately model actual energy performance measured in the facility. This Option usually requires considerable skill in calibrated simulation. Typical applications may include measurement of a facility where several ESSs have been implemented, but no historical energy data is available.
However, IPMVP methodologies summarized above are best suited only for those retrofits in which some assets are replaced or modified. Instead, the retrofits in which energy savings are generated purely on account of operational ESS, like schedule management, set-point management, asset performance management, capacity management etc., the above methodologies are not suitable.
Also, the IPMVP methodologies may not be suitable for estimation of energy consumption in the distributed sites that involve variations in several other parameters like sales, age of the asset, ambient temperature, operating hours in different day of week etc. Further, in certain circumstances, the energy consumption across the distributed sites may go up due to higher business intensity in the service window irrespective of the energy control measures.
The challenges mainly faced during determining energy savings target for the distributed sites of an entity includes generating energy coefficients associated with an energy profile of the distributed sites and computing energy savings across the distributed based on the energy coefficients and adjustment factors.